形容词形式是pointless，例如：
1.The ground is completely saturated: it would be pointless to plant anything.地已经浸透，种什么东西都是白搭。
2.In the end it proved a pointless exercise.这最终证明是一项毫无意义的活动。
3.We searched until we knew it would be pointless to continue.我们搜索又搜索，直到觉得继续下去也枉然时才罢手。
